1. Field of the Invention
The invention concerns shielding bands designed to be fitted to connector housings to provide electrical continuity between the male and female members in order to protect the electrical terminals and the signals that they convey from external electromagnetic interference.
2. Description of the Prior Art
The male and female housings of electrical connectors are coupled according to the male member/female member principle. They are manufactured in metal or an electrically conductive composite material and surround the insulative members carrying the electrical terminals and which are set back from the housing interface so that the latter are coupled and located automatically before the terminals are connected.
The shielding band may be implemented in various designs but usually comprises a succession of elastically deformable contact blades positioned in an annular groove formed on the outside surface of the projecting body of the male member, said blades being fixed into this groove by flexible or rigid coupling means.
In the disclosure of the patent U.S. Pat. No. 4,874,337, the contact blades are spring metal parts which are of flattened V-shape with the open side facing towards the female member. They are retained in the groove on the male member by one or more elastic bands pressing the base of the V into the groove whilst leaving its branches free. The ends of the branches are curved outwardly and before the male member is connected to the female member they project from the periphery of the projecting body of the male member. When the male and female housings are coupled (which is facilitated by annular bevels formed at the respective entry of each of the two members) the curved parts of the elastic wings of the spring blades enter in positive contact with the inside wall of the female member which causes them to retract partially towards the back of the groove in which the contact blades are located. The branches of the blades are therefore elastically stressed at all times the two housings are coupled together and the shielding electrical contact is made before the terminals are connected in order to protect them from any electromagnetic interference.
In the disclosure of the patent U.S. Pat. No. 4,975,085 the contact blades comprise a strip of spring metal slightly curved at the center to form a flared cup the two branches of which are bent through 180.degree. hairpin-fashion to define two contact wings projecting from the periphery of the projecting body of the male member. These elastic blades are linked together by an uncut portion of the initial metal strip and are fixed into the back of the groove by a plate resting on a shoulder formed at the entry of said groove and fixed to the strip supporting the contact blades by crimping, clipping, brazing or adhesive bonding.
The major drawback of the prior art shielding bands lies essentially in the difficulty of fitting them to the respective housing body. The connector housings, as used in aeronautical applications, among others, are usually relatively inaccessible and it is periodically necessary to change the shielding bands. It is therefore extremely desirable for the mounting and demounting of such bands to be as easy as possible so that the operator is not required to demount the connector completely. Prior art shielding bands and in particular those described hereinabove use a multitude of separate and independent parts (contact blades, flexible connecting members, crimped or clipped plate, etc) and fitting them to the connector housing body is particularly laborious especially when it is necessary to fit connecting members to independent contact blades that are difficult to position individually on their respective seats or when it is necessary to crimp, clip or glue the fixing means in a difficultly accessible place.